EP0208515B1 - Procédé et dispositif de filtration - Google Patents

Procédé et dispositif de filtration Download PDF

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Publication number
EP0208515B1
EP0208515B1 EP86305178A EP86305178A EP0208515B1 EP 0208515 B1 EP0208515 B1 EP 0208515B1 EP 86305178 A EP86305178 A EP 86305178A EP 86305178 A EP86305178 A EP 86305178A EP 0208515 B1 EP0208515 B1 EP 0208515B1
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EP
European Patent Office
Prior art keywords
filter
pore size
layer
fibrous layer
aerosol
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP86305178A
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German (de)
English (en)
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EP0208515A3 (en
EP0208515A2 (fr
Inventor
John David Miller
Even Ernest Koslow
Kenneth M. Williamson
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Pall Corp
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Pall Corp
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Publication of EP0208515A2 publication Critical patent/EP0208515A2/fr
Publication of EP0208515A3 publication Critical patent/EP0208515A3/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2003—Glass or glassy material
    • B01D39/2017—Glass or glassy material the material being filamentary or fibrous
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2411—Filter cartridges
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S55/00—Gas separation
    • Y10S55/25—Agglomerators

Definitions

  • This invention is related to processes for the high efficiency removal of liquid aerosols from gaseous streams and to coalescing filters for carrying out such processes.
  • Coalescing filters are used for a variety of applications.
  • gas coalescers serve to remove aerosol contaminants, both liquid and solid, from gaseous streams, for example, in purifying compressed gases such as air, helium, hydrogen, nitrogen, carbon dioxide, and natural gas, and in filtering inert gases used in recovering oil. They also may be used to collect liquid aerosol contaminants, such as in the filtering of vacuum pump exhausts where they serve to both prevent contamination of the environment and reclaim expensive vacuum pump oil. Similarly, they may be used in filtering chemical mists from low pressure chemical process streams to prevent pollution by, and to reclaim, liquid chemical aerosols.
  • coalescing filters are relied upon to remove the most difficult to separate aerosols.
  • oil lubricated compressors are widely used for compressing gases. Such compressors produce aerosols as a result of mechanical shearing and a combination of oil vaporization and subsequent downstream condensation.
  • the aerosols formed generally comprise particles ranging in size from 0.01 to 50 micrometers.
  • Water aerosols are formed when the intake gas to a compressor contains sufficient water vapor that the resulting compressed and cooled gas exceeds 100 percent relative humidity. This commonly occurs, e.g., when the intake gas is atmospheric air or when the gas to be compressed is process gas that has come in contact with water.
  • Highly hydrophobic filters also referred to as “barrier filters” are sometimes used to remove water-based aerosols of relatively large particle size from gas streams. These filters work by preventing water from passing through the filter medium by trapping the water-based aerosols on the upstream surface of the medium. The pores of such barrier filters must be smaller than the aerosol particles being removed. Accordingly, they are not efficient for removal of small aerosol particles since the pressure drop would be prohibitive.
  • Aerosol particles Larger aerosol particles (larger than 0.6 micrometers) tend to impinge and coalesce on surfaces throughout piping systems because their momentum often is too great to follow the flow path. These larger particles may be removed and, for economic reasons, generally are removed by other separating means, e.g., after-coolers and centrifugal separators or demisters. Coalescing filter elements, however, typically must be relied upon to remove aerosol particles ranging in size from 0.1 to 0.6 micrometers. Such aerosols are considered to be the most difficult to separate because they display marginal impactive removal and do not have sufficient diffusional characteristics to divert from system flow to allow interaction with separating devices. Smaller aerosol particles, e.g., less than 0.1 micrometer, typically can be removed with somewhat coarser filters because they rapidly diffuse to surrounding surfaces.
  • coalescing filters conventionally are designed with well-known principles in mind.
  • the filtering efficiency generally increases as the pore size decreases and/or the thickness of the filter medium increases. Decreasing pore size and/or increasing filter medium thickness, however, increases the pressure drop across the medium and, thereby, the energy required to maintain a given flow rate.
  • a given volume or space constraint e.g., a filter cartridge of specified size
  • the use of a thicker filter medium will generally result in limiting available filter surface area, an increase in overall flow velocity, and correspondingly higher flow resistance. Increased flow velocity through the filter also decreases separation efficiency for the difficult-to-remove-size aerosol particles.
  • coalescing filter media have been designed to trade-off and optimize these competing factors. Many filter media so designed offer good performance under dry conditions. Eventually, however, the medium accumulates liquid as a result of collecting liquid aerosol particles. The accumulated liquid tends to block the smaller pores and thereby reduce the filtering efficiency of the medium. Blocked pores also increase the pressure drop across the medium which, in turn, increases energy requirements.
  • coalescing filters not only exhibit reduced efficiency and increased pressure drops when wet, they also tend to produce secondary aerosols. These can be formed by two mechanisms. As the smaller pores are blocked, the velocity of gas through the larger unblocked pores increases. The increased velocity increases the likelihood of shearing liquids from the surface of the filter medium and forming secondary aerosols downstream of the filter. Additionally, as the coalesced liquid flows down the filter, it can form a film over the pores. Gas passing through the filter tends to expel the liquid by forming bubbles which burst, forming secondary aerosols downstream of the filter. In short, the overall performance of the filter medium suffers when wetted.
  • GB-A-2017774 discloses a fibre filter for the elimination of fine mists from gases comprising glass fibres coated with a fluorosilicone to mitigate problems arising from the use of non-wettable fibres.
  • At least some solid particulate matter is generally present in gaseous streams being treated for removal of liquid aerosols. Such dirt may be associated with gas to be filtered or can arise as a result of wear and corrosion of the system apparatus. This solid particulate matter will also block pores in the filter medium and contribute to increased pressure drop.
  • a high performance coalescing filter should have the following characteristics:
  • the subject invention is directed to processes for the high efficiency removal of liquid aerosols from gaseous streams and to coalescing filters which maintain high efficiency and low pressure drop even when operating under wet conditions and which in large measure have the characteristics (1 )-(4) set out above.
  • This invention is directed to processes for filtering liquid aerosol from a gaseous stream.
  • the processes comprise passing the liquid aerosol-containing gaseous stream through a coalescing filter, the filter comprising a porous medium having a critical surface energy less than the surface tension of the liquid to be removed.
  • the dynamic film thickness (t) of the liquid to be removed is from 0.5 D to 0.8 D, where D is the pore size of the porous medium, whereby, in operation, the correlation of pore size with the dynamic film thickness of the liquid coupled with the relationship between the surface tension of the liquid and the critical surface energy of the porous medium provide high efficiency removal of the liquid aerosol.
  • This invention is also directed to coalescing filters capable of removing water aerosols (or oil aerosols) from gaseous streams with high efficiency.
  • the filters comprise three layers, (a) an intermediate fibrous layer having a pore size such that the dynamic film thickness (t) of water (or oil) is from 0.5 D to 0.8 D, where D is the pore size of the intermediate fibrous layer, the fibers of said intermediate fibrous layer having diameters ranging from 0.1 to 20 micrometers, (b) a fibrous layer upstream of the intermediate layer having a pore size greater than the intermediate layer, and (c) a downstream fibrous layer having a pore size greater than the intermediate layer.
  • the critical surface energies of each layer of the filters for removing water aerosols are less than the surface tension of water.
  • the critical surface energies of each layer of the filters for removing oil aerosols are less than the surface tension of oil.
  • the processes provide high efficiency removal of aerosols with a minimum resistance to flow even when wet.
  • the effluent typically contains 0.05 ppm or less, by weight, of aerosol.
  • critical surface energy of the porous medium Y sl
  • Y sl critical surface energy of the porous medium
  • the term "surface tension" of the liquid to be removed is defined as the energy required to generate a unit area of surface displacing the system gas, i.e., relative to the gas phase. This can be determined by a conventional method, e.g., the ring-pull method.
  • dynamic film thickness of the liquid to be removed is defined as the maximum thickness of the liquid in the medium pores where the energy required to divert the gas stream around the liquid is less than the energy required to overcome the adhesion and frictional interactions to move the liquid.
  • the dynamic film thickness can be determined (in laminar flow) from the relationship: where
  • the term "pore size" of the filter medium is defined as the mean or average equivalent diameter of the flow channel between the medium surfaces or opposing walls of the structure making up the medium, e.g., the mean or average distance between fibers when a fibrous filter structure is used. This is analogous to the hydraulic radius treatment for an irregular-shaped channel for fluid flow. For best results, the distribution about the mean pore size should be relatively narrow in a given filter layer.
  • the term "high efficiency" is defined as the removal of the particular aerosol to a level below 0.05 ppm by weight in the effluent.
  • the measurement of the aerosol content in the filtrate is carried out using the method disclosed in the publication PEDD-FSR 101a referred to above.
  • Coalescing filters in accordance with the subject invention which are useful in the processes in accordance with the subject invention preferably comprise porous fibrous media.
  • the filters may have constant pore size or tapered pore sizes, and they may be composite structures comprising multiple filter medium layers and/or multiple support layers. At least one of the layers of the filter media is designed so that the dynamic film thickness (t) of the liquid to be removed is from 0.5 D to 0.8 D (where D is the pore diameter as defined above).
  • the pore size of this layer (or layers) will be from 1 to 5 micrometers when used to filter oil-based aerosols.
  • the pore size will typically be in the range of from 1 to 20 micrometers, more preferably from 4 to 20 micrometers.
  • the dynamic film thickness of the liquid to be removed should be at least 0.5 D. Additionally, the filter medium must have the defined critical surface energy, i.e., be lower than the surface tension of the liquid to be removed.
  • the entire structure that comes in contact with the gas being filtered has the defined critical surface energy, including the support layers and, in the case of a filter cartridge, the end caps.
  • the defined critical surface energy including the support layers and, in the case of a filter cartridge, the end caps.
  • Fibrous filter media in accordance with the subject invention may be made from organic or inorganic fibers.
  • Exemplary organic microfibers include those made from polyolefins, for example, polyethylene, polypropylene, polymethylpentane, polyisobutylene, and copolymers thereof, for example, ethylenepropylene, polyesters, for example, polybutylene terephthalate and polyethylene terephthalate, and polyamides, for example, polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), nylon 11 (prepared from 11-amino-nonanolic acid), and homopolymers of poly-e-caprolactam (nylon 6), and mixtures or blends of such polymers.
  • the microfibers may be made of other polymers which can be formed into microfibers, and mixtures of microfibers also can be used.
  • Exemplary inorganic fibers include those made from glass and metal titanates, e.g., potassium titan
  • the fibers generally will have diameters of from 0.1 to 20 micrometers, although finer or coarser fibers may be used.
  • the fibers may vary in length from relatively short staple-like microfibers of 1.3 cm (0.5 inch) or less up to substantially continuous filaments a meter (several feet) or more in length.
  • the median length to diameter ratio of the fibers (aspect ratio) will be in the range of from 500 to 1,000.
  • Potassium titanate fibers are available from commercial manufacturers, such as Otsuka Chemical Company, Ltd. (Japan) and E. I. DuPont de Nemours and Company. Suitable glass fibers are available from commercial manufacturers, such as PPG Industries, Johns-Mansville, Inc., and Owen-Corning Fiberglass Corporation, as well as other manufacturers.
  • Porous fibrous media may be prepared from a slurry of the fibers and a suitable binder.
  • the slurry typically is cast or drawn by a vacuum onto a screen and then dried and cured.
  • the fibrous media may be made by a melt-blown process, as described in the literature, for example, in 48 (No. 8) Industrial and Engineering Chemistry, 1342-46 (1956), and V. White, The Manufacture of Superfine Organic Fibers, (U.S. Department of Commerce, Naval Research Laboratory, Publication PB111437, 1954).
  • the material of which the media is primarily composed may be selected so that the resulting media will have surface properties in accordance with the present invention. Generally, however, it may be less expensive and more expeditious simply to modify commercially available coalescing filter media. It also may be desirable in that structural, non-shedding, and other beneficial features of media may be achieved where the component materials otherwise would not produce a medium having the defined surface energies.
  • the surface properties of conventional coalescing filter media may be modified by any of a number of well-known surface-modifying or treating agents.
  • Treating agents which may be used to provide filters with the requisite critical surface energy can be any treating agent which imparts the requisite properties.
  • the preferred fluorochemicals can have varied chemical structures, see, for example, U.S. Patent 3,489,148 and the patents cited therein at column 4.
  • Particularly preferred compositions contain perfluorinated fluorochemicals. These type materials are available from Minnesota Mining and Manufacturing Company under the designations FC-721, FC-807, FC-809, and FC-824. The actives in FC-807 and FC-809 are described in detail in the Federal Register, Volume 37, Number 96, at pages 9762-9763.
  • liquid-based compositions containing as the active solids a minimum of 40 percent of ammonium bis(N-ethyl-2-perfluoroalkylsulfoamideoethyl) phosphates wherein the alkyl group is more than 95 percent C s and the fluorine content is from 50.1 to 52.8 percent by weight.
  • FC-824 is a per f luoroacrylate copolymer.
  • These treating materials are preferably applied in the form of a dilute mixture comprising, e.g., 7 parts by volume of water, 0.5 parts by volume of diethylene glycol monobutyl ether (available from Union Carbide Corporation under the trademark Butyl Carbitol) as a fugitive wetting agent, and 2.5 parts by volume of the fluorochemical treating agent (which typically will contain 40 percent by weight solids or more).
  • the 2.5 parts by volume referred to above is based on the total volume of the fluorochemical treating agent, e.g., FC-824, as received from the manufacturer.
  • the water and diethylene glycol monobutyl ether should be premixed and the fluorochemical treating agent slowly added to this first mixture with mixing.
  • FC-721 a clear mobile solution of a fluoropolymer similar to a fluorinated methacrylate polymer.
  • FC-721 is preferably applied to the filter structure to be treated by diluting 2 parts by weight of the material as provided, i.e., a 2 weight percent solids or actives dissolved in Freon TF (trifluorotrichloroethane), with 198 parts by weight of Freon TF. This dilute composition is then applied to a filter medium or structure by any of the methods described below.
  • the surface-modifying agent may be applied to a filter medium or preformed structure, e.g., a filter cartridge, by a post-treatment of the formed medium or structure, for example, by dipping it, spraying it, roller coating it, or otherwise contacting the preformed medium or structure with a solution or dispersion of the surface-modifying agent.
  • a filter medium or preformed structure e.g., a filter cartridge
  • the surface-modifying agent may be admixed into the slurry prior to laydown and formation of a filter medium.
  • the composite medium After the composite medium has been treated, e.g., by impregnation, spraying or roller coating the dilute treating agent onto the structure, it is then dried.
  • the filter medium if it is to be used in filtration of oil aerosols, should yield a minimum contact angle of 100, and preferably a contact angle of between 100 and 140, degrees with mineral oil when measured by the Sessile Drop Method.
  • This known method involves the measurement of the tangent angle of a stationary drop of oil resting on a flat surface of the medium being tested by means of a microscope.
  • a minimum contact angle of 100, and preferably a contact angle of between 100 and 140, degrees with water should be obtained.
  • the coalescing filter structures can take a variety of forms including those of conventional coalescing filter structures, for example, discs, flat panels, and pleated or unpleated cylinders. They may also comprise simple or composite media.
  • a preferred filter element comprises a cylindrical filter structure 10 and end caps 11 and 12.
  • the gaseous stream passes through an opening (not shown) in the end cap 12 into the interior of the cylindrical element and, since the end cap 11 is solid, the gaseous stream passes through the filter structure 10 to the exterior.
  • the filter element depicted in Figure 1 may be enclosed within a housing (not shown) wherein the aerosol which coalesces on the filter structure 10 is carried down the outer side of the filter structure by gravity to a sump or collector at the bottom.
  • the filter structure 10 may comprise a single pleated filter medium 14 supported by an outer perforated support cage 13.
  • the filter structure 10 may comprise an outer coarse filter medium 15 which acts to trap solid particulates, a perforated support cage 16 and an inner filter medium 17.
  • Filter media 15 and 17 in the preferred embodiment structures depicted in the drawings are fibrous media of the type described above.
  • the outer medium 15 preferably has a relatively large pore size
  • the inner medium 17 preferably has a tapered pore structure from relatively large to relatively small and then back to relatively large; the first large pore portion to provide dirt capacity, the intermediate small pore portion for efficient aerosol removal, and the second large pore portion to aid in coalescence.
  • the pleated inner medium 18 preferably has a tapered pore structure from coarse to fine and back to coarse.
  • FIG. 3 Another example of an inside/out filter element configuration is illustrated in Figure 3.
  • this filter element there are three filter layers over the perforated support core 40:
  • coalescing filter structures as well as a variety of coalescing filter media are suitable.
  • the filter media e.g., a filter cartridge or element including any end caps, support cage, or core, have critical surface energies less than the surface tension of the liquid to be removed, whether as a result of appropriate selection of the composite materials or of treatment to modify the surface properties.
  • a composite, cylindrical pleated filter structure consisting of four oleophobic layers and having pleats 0.725 cm (0.285 inch) deep, a total of 60 corrugations, a length of 24.1 cm (9.5 inches), and having an effective filter surface area of 0.107 square meter (1.15 square foot) was prepared from two layers of melt-blown polyester fibrous material with two glass fiber layers sandwiched therebetween.
  • the melt-blown polyester fibrous layers were identical and were comprised of fibers having diameters ranging from 35 to 50 micrometers.
  • the melt-blown polyester fibrous material had a flat sheet weight of 1.61 grams per square meter (1.35 grams per square yard) and was calendered to a thickness of 0.023 cm (0.009 inch) prior to being combined with the glass fiber medium.
  • the calendered material had a pore size of about 100 micrometers.
  • the intermediate glass fiber layers were comprised of epoxy bonded glass fibers ranging in diameter from 0.2 to 1.6 micrometers.
  • the glass fiber layers each had a flat sheet weight of 95.8 grams per square meter (8.9 grams per square foot) and was about 0.05 cm (0.02 inch) thick with pore sizes in the range of from 1 to 5 micrometers, treated with 2.5 parts by weight FC 824, 7 parts by weight water, and 0.5 parts by weight Butylcarbitol gas.
  • the pleated composite filter structure was placed inside an open, perforated polypropylene cage and a polypropylene web was air-laid around the perforated cage. The thickness of this outer web was about 0.635 cm (0.25 inch).
  • the fibers in the outer wrapped web had diameters ranging from 20 to 30 micrometers.
  • the pore size was about 1,000 micrometers.
  • the resulting structure had a cross-sectional configuration as depicted in Figure 2b with the pleated medium 18 made up of four layers, as described.
  • the polypropylene web and cage described above was given an oleophobic post-treatment comprising saturating the component with a 0.04 weight percent Florad FC721, i.e., four parts by weight of the material as received was diluted with 196 parts by weight of Freon TF. After vacuum application to remove excess treating material, the structure was dried at ambient conditions. The resulting structure had a minimum contact angle of 130 degrees with mineral oil when measured by the Sessile drop method, i.e., the measurement of the tangent angle of a stationary drop of the oil resting on a flat surface by use of a microscope.
  • the described filter element or cartridge having the same cross-sectional configuration as depicted in Figure 2b was prepared.
  • the various layers making up the filter structure (presented in an outside basis) and their characteristics are set out in Table 2 below.
  • the filter element was tested by the method described in PEDD-FSR 101a using, as the challenge, an oil aerosol derived from Mobil DTE 24 oil with a weight concentration of the aerosol in the influent gas stream of 135 ppm by weight. An average flow rate of 5.7 liters/second, an average pressure of 3.87 Kg/cm 2 gauge and an average temperature of 20 degrees Centigrade was used. The concentration of the oil in the effluent was 0.0025 ppm by weight.
  • the clean filter element had a pressure drop (AP) of 34.3 g/cm 2 (0.488 psid). Its saturated pressure drop was 79.4 g/cm 2 (1.13 psid).
  • the clean assembly pressure drop was 55.4 g/cm 2 (0.788 psid) and the loaded or saturated assembly pressure drop was 100.5 g/cm 2 (1.43 psid).
  • a performance number of 181 was obtained (about twice that of conventional coalescers of the same configuration).
  • Two identical, composite, cylindrical pleated filter structures having pleats 1.0 cm (0.4 inches) deep, a total of 56 corrugations, 23.5 cm (9.25 inches) in length, and having an effective filter surface of 0.268 square meters (2.88 square feet) were prepared from (in the direction of flow, i.e., inside out) seven layers of melt-blown polyester fibrous material having fibers ranging in diameter from 35 to 50 micrometers and a pore size of about 100 micrometers, with each layer calendered to 0.01 cm (0.004 inches) in thickness and having a flat sheet density of 17.0 grams per square meter (0.5 ounces per square yard), followed by one layer of a phenolic bonded glass fiber medium with fibers ranging from 0.2 to 1.6 micrometers and having a flat sheet weight of 29 grams per square meter (2.7 grams per square foot) and a thickness of about 0.025 cm (0.01 inches) with the pore sizes ranging from 1 to 5 micrometers, followed by a melt-blown polyester fibrous layer with fiber diameters
  • the untreated filter structures had much higher pressure differentials under the test conditions than did the treated filter structures.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
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  • Life Sciences & Earth Sciences (AREA)
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Claims (13)

1. Un procédé pour filtrer un aérosol liquide à partir d'un courant gazeux qui consiste à faire passer le courant gazeux contenant l'aérosol liquide à travers un filtre par coalescence, ledit filtre comprenant un milieu poreux ayant une énergie critique de surface inférieure à la tension superficielle du liquide à éliminer et l'épaisseur dynamique du film (t) du liquide à éliminer est de 0,5 D à 0,8 D, où D est la taille de pores dudit milieu poreux, de sorte que, en opération, la corrélation entre la taille de pores dudit milieu poreux et l'épaisseur dynamique du film dudit liquide couplée avec la relation entre la tension superficielle dudit liquide et l'énergie critique de surface dudit milieu poreux fournit une grande efficacité d'élimination dudit aérosol liquide.
2. Le procédé selon la revendication 1, selon lequel ledit milieu poreux est un milieu fibreux poreux.
3. Le procédé selon la revendication 2, selon lequel ledit aérosol est un aérosol huileux.
4. Le procédé selon la revendication 2 ou 3, selo lequel ledit milieu fibreux poreux a une taille de pores de 1 à 5 pm et une énergie critique de surface telle que l'angle de contact (trois phases) est compris entre 100 et 140° avec l'huile minérale.
5. Le procédé selon l'une quelconque des revendications 1-4, selon lequel ledit filtre par coalescence comprend trois couches, (a) ledit milieu poreux comme couche fibreuse intermédiaire, (b) une couche fibreuse en amont ayant une taille de pores supérieure à celle de ladite couche fibreuse intermédiaire, et (c) une couche fibreuse en aval ayant une taille de pores supérieure à celle de ladite couche intermédiaire.
6. Le procédé selon la revendication 2, selon lequel ledit aérosol est un aérosol aqueux.
7. Le procédé selon la revendication 2 ou 6, selon lequel ledit milieu fibreux poreux a une taille de pores de 1 à 20 pm et une énergie critique de surface telle que l'angle de contact (trois phases) est d'au moins 100° avec l'eau.
8. Le procédé selon l'une quelconque des revendications 1-7, selon lequel ledit milieu poreux comprend des fibres et lesdites fibres sont des fibres de verre, de polyoléfine, de polyester, de polyamide, ou des mélanges de celles-ci et selon lequel lesdites fibres ont été modifiées par un composé fluorochimique pour réduire leur énergie critique de surface à une valeur inférieure à l'énergie critique de surface du liquide à éliminer.
9. Le procédé selon l'une quelconque des revendications 1-8, selon lequel la résistance à l'écoulement dudit courant à travers ledit filtre est de 7,0 à 140 g/cm2 (différentiel) ou moins.
10. Un filtre par coalescence pour l'élimination avec une grande efficacité d'un aérosol aqueux à partir d'un courant gazeux, ledit filtre comprenant trois couches, (a) une couche fibreuse intermédiaire ayant une taille de pores telle que l'épaisseur dynamique du film (t) d'eau est de 0,5 D à 0,8 D, où D est la taille de pores de la couche fibreuse intermédiaire, les fibres de cette couche fibreuse intermédiaire ayant des diamètres compris dans l'intervalle de 0,1 à 20 pm, (b) une couche fibreuse en amont de ladite couche intermédiaire ayant une taille de pores supérieure à celle de ladite couche intermédiaire, et (c) une couche fibreuse en aval ayant une tialle de pores supérieure à celle de ladite couche intermédiaire et selon lequel l'énergie critique de surface de chaque couche dudit filtre est inférieure à la tension superficielle de l'eau.
11. Un filtre par coalescence pour l'élimination avec une grande efficacité d'un aérosol huileux à partir d'un courant gazeux, ledit filtre comprenant trois couches, (a) une couche fibreuse intermédiaire ayant une taille de pores telle que l'épaisseur dynamique du film (t) d'huile est de 0,5 D à 0,8 D, où D est la taille de pores de la couche fibreuse intermédiaire, les fibres de ladite couche fibreuse intermédiaire ayant des diamètres compris dans l'intervalle de 0,1 à 20 um, (b) une couche fibreuse en amont de ladite couche intermédiaire ayant une taille de pores supérieure à ladite couche intermédiaire, et (c) une couche fibreuse en aval ayant une taille de pores supérieure à celle de ladite couche intermédiaire et selon lequel l'énergie critique de surface de chaque couche dudit filtre est inférieure à la tension superficielle de l'huile.
12. Une cartouche filtrante comprenant le filtre par coalescence de la revendication 10 ou 11 et incluant en outre un noyau, une cage de support et des couvercles d'extrémité.
13. La cartouche filtrante selon la revendication 12, selon laquelle toutes les parties de ladite cartouche ont des énergies critiques de surface inférieures à la tension superficielle de l'huile.
EP86305178A 1985-07-05 1986-07-03 Procédé et dispositif de filtration Expired EP0208515B1 (fr)

Applications Claiming Priority (2)

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US751953 1985-07-05
US06/751,953 US4676807A (en) 1985-07-05 1985-07-05 Process for removal of liquid aerosols from gaseous streams

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EP0208515A2 EP0208515A2 (fr) 1987-01-14
EP0208515A3 EP0208515A3 (en) 1987-08-26
EP0208515B1 true EP0208515B1 (fr) 1990-10-03

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US (1) US4676807A (fr)
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JP (1) JPS6257626A (fr)
CA (1) CA1277252C (fr)
DE (1) DE3674656D1 (fr)
GB (1) GB2177019B (fr)

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US5858044A (en) 1996-07-11 1999-01-12 Donaldson Company, Inc. Filter arrangement including removable filter with first and second media secured together
USD404807S (en) 1996-07-11 1999-01-26 Donaldson Company, Inc. Filter sleeve
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Also Published As

Publication number Publication date
EP0208515A3 (en) 1987-08-26
EP0208515A2 (fr) 1987-01-14
CA1277252C (fr) 1990-12-04
JPS6257626A (ja) 1987-03-13
US4676807A (en) 1987-06-30
DE3674656D1 (de) 1990-11-08
GB8616234D0 (en) 1986-08-13
GB2177019A (en) 1987-01-14
GB2177019B (en) 1989-07-19

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